The efficacy of the development and of the developer depend on many factors, including the degree to which the developer has been used, or "seasoned". As it is used, the developer gains substances coming from the photographic film being processed, and is oxidized. Oxidation is the cumulative effect of the development (reduction of the silver halides) and contact with the air. The oxidation of the developer, that is, oxidation of the reducing substances which it contains, in particular the developing agents, impairs its efficacy and consequently requires the developer to be regenerated (or renewed) at regular intervals in order to maintain the sensitometric characteristics of the photographic films being processed and to prevent the formation of stain. In order to minimize the effects of aerial oxidation, which occurs even when the developer is not in use, large quantities of sulfite or bisulphite are usually incorporated in the developer (up to 100 g/l or more).
Even with sulfite added, developers suffer the effects of aerial oxidation. Also, this oxidation results in the transformation of the sulfite into sulphate, which must be then eliminated to allow recycling the developer, or discharging it to the drains.
The object of the present invention is a method of solving the aforementioned problem, that is, a method which makes it possible to minimize the aerial oxidation of a photographic developer by reducing the oxygen content in the vicinity of the free surface of the bath of photographic developer.